Copper wire is the most commonly material for making transformer windings. Graphene is an ideal reinforcement phase for improving the performance of copper wires, and has a hot focus in the field of new transformer materials. The hot-pressing process of graphene copper matrix composites is a method of using graphene to strengthen copper matrix. In this paper, hot pressing process of graphene/copper composites has been adopt hot at the pressure of 20, 30, 40, and 50 MPa; hot pressing temperature 700, 800,900 and 1000 ℃. The results shows that the addition of graphene has a positive effect on the electrical conductivity of the composite material. The conductivity of the graphene/copper composite material will be enhanced by this hot-pressing process. According to the Kelvin Probe Force Microscopy (KPFM) test, the interface of the graphene/copper composites is improved by hot pressing process to the benefit of the electrical conductivity of the composites.